Apparatus for abrading by extrusion and abrading medium

ABSTRACT

An abrasive medium is described consisting of finely divided abrasive particles uniformly distributed in a semifolid, difficulty flowable rubberlike plastic material of the consistency of putty and which forms a substantially solid matrix in carrying out the method of this invention which comprises forcing the medium over an internal surface in abrading contact therewith Representatives of such plastic material are silicone putty or silicone rubber and a nonvulcanized plastic rubberlike putty. Two forms of apparatus for carrying out the method are disclosed. The workpiece is held between two cylinders with an opening through the workpiece in communication with the adjacent cylinder chambers in which reciprocating pistons move the medium alternately from one cylinder through the workpiece opening into the other cylinder.



2. Apparatus as defined in claim 1 wherein each of said devices comprises a double-acting cylinder and piston motor, a plastic material cylinder horizontally aligned with its associated motor cylinder, each said motor cylinder having a piston rod extending outwardly toward said workpiece holder and a plunger on said rod snugly fitting into its associated plastic material cylinder, the plastic material cylinder of said other device having a mounting permitting cylinder movement longitudinally away from said workpiece, said workpiece-holding means comprising means urging said other plastic material cylinder toward and against said workpiece to clamp it between said devices, and control means for said other device for causing it to lift said cylinder after said flow of said plastic material in said opposite direction against said urging means sufficiently to release said workpiece.
 3. Apparatus as defined in claim 2, wherein said means urging said other plastic material cylinder against said workpiece is a spring held by said frame, and said control means for said other device includes means for causing its plunger to traverse its coacting cylinder away from said workpiece against the urging of said spring sufficiently to release said workpiece.
 4. Apparatus as defined in claim 2, wherein said means urging said other plastic material cylinder against said workpiece is a pressure-fluid-actuated motor having means for urging said other plastic material cylinder toward and against said workpiece, and said control means for said other device includes means for causing said pressure-fluid-actuated motor to move said other plastic material cylinder away from said workpiece sufficiently to release said workpiece.
 5. Apparatus as defined in claim 1 wherein said means causing said devices to force said plastic material first in one direction and then in the opposite direction includes a double-acting cylinder and piston motor for each device and control means for causing each of said motors in turn to cause flow of said plastic material through said workpiece.
 6. Apparatus as defined in claim 5, wherein said control means comprises an actuator inside the cylinder of one of said motors engageable and movable to an actuated position by said associated piston near the end of its travel in a direction causing flow of said plastic material through said workpiece, and means operatively associated with said actuator in its actuated position for causing at least one of said devices to reverse the motion of its motor.
 7. Apparatus as defined in claim 6 wherein said actuator comprises a button reciprocatably mounted in the cylinder head of said one motor and normally extending into said cylinder in position to be engaged and moved longitudinally of said cylinder by the approaching piston, spring means urging said button into said cylinder, means sealing said button in said cylinder head against leakage of pressure fluid out of said cylinder and a member carried by said button and exteriorly out through said head and adapted to operate a control member. 